Underground boreholes are formed or used in various industries, such as hydrocarbon exploration and production wells. In the oilfield industry, for example, such wells are often formed with a “cellar” located at its upper end. The cellar is a dug-out area, or pit, at the top of the borehole which often has inner earthen walls lined with wood, cement, pipe or other material. The cellar is typically wider than the borehole and may provide additional height between the rig floor and the well head. The cellar may be useful, for example, to collect drainage water and other liquids for disposal, accommodate the installation of and/or provide access to one or more wellhead components, such as a casing spool, casing head, BOP, or other purposes.
It is often desirable to provide a liquid-tight seal around the opening to an underground borehole, such as to prevent the liquids form spilling out of the borehole onto the earth or subgrade terrain adjacent to the borehole. Sometimes, temporary or semi-permanent support surfaces are used around the borehole site. In instances where a support surface is located proximate to an underground borehole, it may likewise be desirable to provide a liquid-tight seal at the juncture of the support surface and the underground borehole, such as to prevent the liquids disposed on the support surface or within the borehole from contacting or contaminating the earth adjacent to the borehole or beneath the adjacent support surface.
Traditionally, a plastic liner is placed around the borehole (and around or below adjacent mats when a support surface is used) in an effort to capture liquids overflowing from the borehole (or introduced onto the support surface) before such liquids encounter the subgrade terrain. The use of liners may have one or more disadvantages. In many instances, the liners are not reusable and must often be discarded. This can be problematic because landfill operators have expressed disinterest in accepting used liners on the basis that they are bulky and require excessive landfill space, or for other reasons. Thus, it can be difficult to find suitable, cost-effective ways to dispose of the liners. For another example, the plastic liners are sometimes ineffective at preventing liquid leakage into the subgrade terrain or allowing effective clean-up, which can cause other problems and require significant time and effort. Thus, there is a need for improved apparatus, systems and methods for preventing liquids from entering the earth adjacent to an underground wellbore.
It should be understood that the above-described features, capabilities and disadvantages are provided for illustrative purposes only and are not intended to limit the scope or subject matter of the appended claims or those of any related patent application or patent. Thus, none of the appended claims or claims of any related application or patent should be limited by the above discussion or construed to address, include or exclude each or any of the above-cited features, capabilities or disadvantages merely because of the mention thereof herein.
Accordingly, there exists a need for improved systems, articles and methods useful in connection with sealing around the opening to an underground borehole having one or more of the attributes or capabilities described or shown in, or as may be apparent from, the various portions of this patent application.